1. Field of the Invention
The present invention relates to an ink jet recording apparatus which discharges ink onto a recording medium thereby recording information on the recording medium. More particularly, the present invention is concerned with an ink jet recording apparatus suitable for use in an information processing apparatus such as a printer, a copying machine, a wordprocessor, or a computer.
2. Description of the Related Art
Recording apparatuses have been known which function as a printer, a copying machine, or a facsimile machine. Recording apparatuses are also used as output devices for composite electronic devices such as a computer or a wordprocessor, as well as for a workstation. Such recording apparatuses are designed and configured to progressively record images including characters and symbols on recording media such as recording paper sheets or plastic sheets, in accordance with given image information. Such known recording apparatuses are classified according to the recording method relied upon: namely, ink-jet-type recording apparatuses, wire-dot-type recording apparatuses, thermal recording apparatuses, laser beam recording apparatuses and so on.
The recording apparatuses are also classified according to the direction of the recording. For instance, a serial-type recording apparatus performs recording while scanning across the recording medium in a main-scan direction that crosses the direction of a sub-scan effected by feeding the recording medium. A recording head moves along the recording medium in the main-scan direction so as to record a series of image portions. When the recording for a single line is finished, the recording medium is fed so as to effect a line-feed in the sub-scan direction by a predetermined pitch of the recording lines. The recording head then commences its movement again in the main-scan direction so as to perform the recording of a series of image portions along the next recording line. This operation is repeated until the recording is finished over a desired area on the recording medium.
In contrast, a line-type recording apparatus performing the recording employs only a sub-scan motion. In this type of recording apparatus, the recording medium is set at a predetermined recording position in the recording apparatus, and the recording of a series of image portions along one recording line is performed at one time while allowing one pitch feed of the recording medium to be performed between the recording operations along successive lines of recording, whereby an image is recorded over a desired area on the recording medium.
The aforementioned ink-jet-type recording apparatus (referred to as an xe2x80x9cink jet recording apparatusxe2x80x9d) performs recording by discharging ink onto the recording medium from the recording head. This type of recording apparatus is superior in that it can perform high-speed recording of highly intricate images by a simple structure of the recording head on ordinary plain paper sheets without necessitating any specific treatment of the paper sheets. In addition, this type of recording apparatus can operate with a reduced cost and at a low level of noise by virtue of its non-impact nature and, further, advantageously permits easy recording of multi-color images with the use of a multiplicity of types of ink of different colors.
Among various kinds of ink jet recording apparatuses, an ink jet recording apparatus of the type which discharges ink by using thermal energy offers an advantage in that a recording head having liquid channels, i.e., liquid discharge nozzle openings, arranged at a high density, can easily be produced. More specifically, such a recording head can be produced by depositing various components such as electro-thermal transducers, electrodes, liquid channel walls, and a top plate on a substrate, by using a semiconductor process including steps such as etching, evaporation, and sputtering. This leads to a more compact structure of the recording head and, hence, of the recording apparatus. Furthermore, elongation and two-dimensional development of the recording head can easily be achieved by advantageously combining IC technologies and micro-machining techniques, enabling easy implementation of full-multi-nozzle recording heads and of high-density packaging of the recording heads.
In the meantime, a variety of demands or requirements are imposed on the materials of the recording media. Studies and attempts have been made to cope with such demands and, nowadays, recording apparatuses are available that perform recording on recording media other than conventionally used paper media (including thin paper sheets and processed paper), such as a thin plastic sheet, e.g., an OHP transparency, leather, non-woven fabric, and a metal sheet.
In general, an ink jet recording apparatus essentially requires that the distance between the recording medium such as a paper sheet and the recording head be maintained within a predetermined tolerance range. To this end, a guide plate known as a platen is used to back and support a recording paper sheet in a recording section of the apparatus. It is often experienced that the recording head discharges the ink in the absence of a recording paper sheet in the recording section, as in the case of the use of the wrong size of paper or sheet feed failure due to a jam. In such a case, the guide support surface of the platen is contaminated with the discharged ink.
Japanese Patent Laid-Open Publication No. 10-337886 discloses an art which is envisaged to eliminate this problem. Referring to FIG. 11, a known recording apparatus of the type disclosed in the above-mentioned patent publication incorporates an ink absorbent 93 arranged behind a plate member 91 that guides a recording paper sheet 90 in the recording section. An aperture 92 is formed in a portion of the plate member 91 opposing the recording head. The aperture 92 extends in the width direction of the recording paper sheet 90 over a length large enough to encompass both widthwise ends of the recording paper sheet 90. In operation, any ink discharged in the absence of the recording paper sheet 90 or directed to a region devoid of the paper sheet 90 is received by the ink absorbent 93 through the aperture 92.
This known recording apparatus still suffers from a problem in that a recording sheet transportation failure tends to be caused by undesirable curling of the recording sheet, particularly when an image is formed by a large number of ink dots deposited at high density in a region of the recording sheet so close to a leading or trailing edge thereof so as to scarcely leave a margin on the recording sheet. This tendency is particularly notable when the recording sheet is thick. In addition, different kinds of recording sheets exhibit different curling behaviors, and an identical recording sheet tends to change its curling direction over time.
Accordingly, it is an object of the present invention to provide an ink jet recording apparatus which allows an image that requires a large amount of ink ejection per unit area to be formed in a region of the recording medium which just falls within predetermined margins of the recording sheet.
It is another object of the present invention to provide a recording apparatus in which left and right end portions of a recording medium are curved away from the recording head, thereby enabling an image to be formed in a region which just falls within predetermined margins of the recording sheet.
It is still another object of the present invention to provide an ink jet recording apparatus having a recording head for discharging ink onto a recording medium thereby performing recording, comprising a transporting roller for transporting the recording medium into a recording section, and an enforcing member disposed upstream of the transporting roller as viewed in the direction of transportation and arranged to force the recording medium to curl into a shape suitable for recording.
It is a further object of the present invention to provide an ink jet recording apparatus having a recording head for discharging ink onto a recording medium thereby performing recording, comprising a transporting roller for transporting the recording medium into a recording section, and an enforcing member disposed upstream of the transporting roller as viewed in the direction of transportation and arranged to impart a tendency to the recording sheet such that both lateral ends of the recording sheet are biased away from the recording head.
To these ends, according to one aspect of the present invention, there is provided a recording apparatus having recording means for effecting recording on a recording medium at a recording zone, the recording apparatus comprising: a transporting roller for transporting the recording medium to the recording zone; and a pre-biasing member disposed upstream of the transporting roller and arranged to impart to the recording medium a curling tendency enabling recording to be performed.
In accordance with another aspect of the present invention, there is provided a recording apparatus having recording means for effecting recording on a recording medium at a recording zone, the recording apparatus comprising: a transporting roller for transporting the recording medium to the recording zone; and a pre-biasing member disposed upstream of the transporting roller relative to the direction of transportation of the recording medium and arranged to provide the recording medium with a tendency such that left and right end portions of the recording medium are biased away from the recording means.
In accordance with still another aspect of the present invention, there is provided a recording apparatus having recording means for effecting recording on a recording medium at a recording zone, the recording apparatus comprising: a transporting roller for transporting the recording medium to the recording zone; a pre-biasing member disposed upstream of the transporting roller relative to the direction of transportation of the recording medium and arranged to provide the recording medium with a tendency such that left and right end portions of the recording medium are biased away from the recording means; a platen having a guiding surface for guiding and supporting the recording medium in the recording section; an aperture formed in the platen and extending in the width direction of the recording medium and having a predetermined width, the aperture being disposed so as to oppose the recording means; and a sloping surface which is disposed in the aperture and extending downstream relative to the direction of transportation of the recording medium.
Preferably, the width of the aperture is smaller than the scanning stroke of the recording head.
The ink jet recording apparatus may further comprise an ink absorbent disposed so as to be exposed through the aperture.
Preferably, the recording head is configured to discharge at least one ink droplet produced by thermal energy, thereby performing recording.
According to yet another aspect of the present invention, a recording apparatus having recording means for effecting recording on a recording medium at a recording zone includes transporting means and pre-biasing means. The transporting means transports the recording medium to the recording zone. The pre-biasing means disposed upstream of the transporting means imparts to the recording medium a curling tendency enabling recording to be performed.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.